Machinability Improvement of Iron Based Sintered Alloys by Adding Complex Oxide Powder for K Grade Carbide Tools

摘要

Generally speaking iron based sintered parts have poor machinability compared with wrought steel. [1] However, this study showed less tool wear with sintered material than wrought steel when using K grade carbide tools. This result is attributed to the protective behavior by built-up edge (B.U.E) and the reduced cutting force from chip crack formation caused by porosity.Although it is well known that manganese sulfide powder (MnS) is effective as machining enhancer for PM, increased admix ratio of MnS is hardly expected further improvement of tool life. On this background the authors developed new free machining additive named 'KSX-2' that offers superior machinability in comparison with traditional MnS mixture. KSX-2 consists of complex oxide that has optimized coefficient of viscosity at cutting temperature. And KSX-2 accelerates to generate B.U.E as protective layer, and reduces cutting force. As a result, the tool life with KSX-2 shows at least 2 times longer compared with conventional MnS admix.